Final answer:
A healthy newborn often loses up to seven percent of their birth weight in the first week due to physiological changes but should subsequently gain weight rapidly. Monitoring consistent growth is essential, and newborns come equipped with reflexes and developmental milestones to ensure their survival and development.
Step-by-step explanation:
During the first week of life, it is normal for a newborn to lose a small percentage of their birth weight. This weight loss can be between three to seven percent of the initial birth weight due to several physiological adjustments, including the resorption and excretion of fluids that were present in the lungs before birth. Additionally, it may take a few days for the newborn's feeding to become established, which also contributes to this initial weight loss.
A healthy, well-nourished newborn, on average, will weigh about 3.4 kg (7.5 lb) and measure around 51 cm (20 in.) in length at birth. After the initial weight loss, an infant should start gaining roughly 20 g (0.7 oz) per day, signifying normal growth. It is also important to monitor the growth of the newborn, not just the actual weight and length numbers, but ensuring they are growing consistently over time.
Newborns possess developed senses of touch and hearing, which they use to interact with their environment. However, their vision is not yet fully developed. Newborns have inherent reflexes like the rooting and suckling reflexes, which are vital for their survival. By the first birthday, a healthy infant typically triples their birth weight and doubles their length, with rapid growth occurring particularly in the head and trunk.